1. Technical Field
The disclosure relates to preparation of solid acids.
2. Description of Related Art
Solid acids are widely used in industry. There are two important types of solid acids, one is acid aluminosilicate zeolite, and the other one is acid resin (such as amberlyst-15 having a polystyrene backbone). However, the pore size of the acid aluminosilicate zeolite is too small to accommodate large medical molecules, and the reaction temperature needed by the acid aluminosilicate zeolite is usually 200-300° C. to present enough acidity. As for the acid resin, the acid resin will be swelled by solvents to affect the effective acid amount, and the thermal stability of the acid resin is kind of poor. Therefore, the acid resin is usually deteriorated after reaction and difficult to be regenerated.